My question involves bankruptcy in the state of: PA

We had filed about a year ago and everything was fine till I lost my job. I have been looking however very difficult because of the distance I have to go with the SUV we can't afford to drive very far. Our payment for this truck is so high we are really hurting so we wanted to know what would happen if we voluntary turn in the truck? What is the law in that while under chapter 13? I appreciate any feedback..Thanks!